[active matrix organic light emitting diode display and fabrication method of the same]

ABSTRACT

n active matrix organic light emitting diode display and a fabrication method of the same. A substrate having a display area and a non-display area is provided. A plurality of pixel structures is formed in the display area, and a plurality of transparent conductive lines to electrically connect the pixel structures are formed on the substrate. The transparent conductive lines extend from the display area to the non-display area. A photosensitive glue is formed at a periphery of the display area, and a cap is formed to cover the display area. The cap is adhered to the substrate using the photosensitive glue. A radiation step is performed on a rear surface of the substrate to cure the photosensitive glue. A driving chip electrically connected to the pixel structures via the transparent conductive lines is formed in the non-display area.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of a prior application Ser. No.10/248,336, filed Jan. 10, 2003, which claims the priority benefit ofTaiwan application serial no. 91133680, filed Nov. 19, 2002.

BACKGROUND OF INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates in general to a flat panel display and afabrication method thereof, and more particularly, to an active matrixorganic light emitting diode (AMOLED) and a fabrication method thereof.

[0004] 2. Related Art of the Invention

[0005] The organic light emitting diode is a semiconductor device withhigh conversion efficiency by converting electric energy into opticalenergy. The common application includes indicators, display panel andlight emitting device for optical pickup head. Having the propertiessuch as viewing-angle independency, simple process, low cost, highresponse speed, broad application temperature range and full color, theorganic light emitting diode meet with the requirement of modern displayand becomes a very popular research topic.

[0006] Following the intensive research, the active matrix organic lightemitting diode having an organic light emitting layer and a cathodelayer formed on a substrate having a thin-film transistor array formedthereon has been developed. The active matrix organic light emittingdiode display is driven by the thin-film transistor. The fabrication ofthe conventional active matrix organic light emitting diode display isintroduced as follows.

[0007]FIG. 1 shows a top view of a conventional active matrix organiclight emitting diode display. FIG. 2 shows a cross sectional view alongline I-I″ of FIG. 1.

[0008] Referring to FIGS. 1 and 2, a substrate 100 on which a displayarea 120 and a non-display area 122 are formed is provided. The displayarea 120 of the substrate 100 further comprises a plurality of pixelstructures 107 arranged as an array thereon. Each of the pixelstructures 107 comprises an active device (thin-film transistor), ananode layer 102, a luminescent layer 104 and a cathode layer 106.

[0009] Each pixel structure 107 is controlled by a scan line (not shown)and a data line (not shown). The scan lines and data lines located inthe display area 120 extends towards the non-display area 122 to form aplurality of fan-outs 108 extending externally. The fan-outs 108 areused to electrically connect the driving chip subsequently formed in thenon-display area 122.

[0010] An ultra-violet (UV) glue 112 is formed at a perimeter of thedisplay area 120 on the substrate 100, while a cap 114 is disposed overthe substrate 100. The substrate 100 and the cap 114 are then adheredvia the UV glue 112. An UV radiation 116 is performed to cure the UVglue 112, so as to seal the display area 122 within the substrate 100and the cap 114. A driving chip 110 is then formed on the non-displayarea 122 of the substrate 100. The driving chip 110 is electricallyconnected to the pixel structures 107 via the fan-outs 108.

[0011] In the conventional process, the fan-outs 108 electricallyconnecting the pixel structures 107 and the driving chip 110 is made ofthe same metal material of the scan lines and the data lines. A part ofthe UV glue 112 is blocked by the fan-outs 108 and unable to absorb theUV radiation 116. Consequently, this part of UV glue 112 is not curedproperly to result in negative effect of the package. That is, moistureis easily to penetrate through the part of UV glue 112 which is curedincompletely to damage the internal device of the display.

SUMMARY OF INVENTION

[0012] The present invention provides an active matrix organic lightemitting diode display and a fabrication method thereof to improve theincomplete packaging problem caused in the conventional structure formedby the conventional fabrication method.

[0013] The method of fabricating an active matrix organic light emittingdiode comprises the following steps. A substrate having a display areaand a non-display area thereon is provided. A plurality of pixelstructures is formed in the display area. Each pixel structure comprisesan active device (thin-film transistor), an anode layer, a luminescentlayer and a cathode layer. A plurality of transparent conductive linesis formed in the non-display area for providing electrical connection tothe pixel structures. The transparent conductive lines can be defined bythe step of forming the anode. The material for forming the transparentconductive lines includes indium tin oxide or indium zinc oxide. Aphotosensitive glue is applied at a perimeter of the display area on thesubstrate. A cap is disposed over the display area of the substrate andadhered to the substrate to cover the display area via thephotosensitive glue. A radiation step is performed to cure thephotosensitive glue. A driving chip is then formed on the non-displayarea and electrically connected to the pixel structures via thetransparent conductive lines.

[0014] The active matrix organic light emitting diode provided by thepresent invention comprises a substrate, a driving chip, a plurality oftransparent conductive lines, a cap and a photosensitive glue. Thesubstrate has a display area and a non-display area, and a plurality ofpixel structures formed in the display area. Each of the pixel structurecomprises an active device (thin-film transistor), an anode layer, aluminescent layer and a cathode layer. The driving chip is formed in thenon-display area of the substrate. The transparent conductive lines aredisposed on the substrate and extend from the display area towards thenon-display area to provide electric connection between the driving chipand the pixel electrodes. The material for forming the transparentconductive lines includes indium tin oxide and indium zinc oxide. Inaddition, the cap is located above the display area of the substrate toencapsulate the pixel structures.

[0015] The present invention uses transparent conductive lines toprovide electric connection between the pixel structures and the drivingchip instead of using the fan-outs described above. Therefore, theproblem of incomplete curing the UV glue is resolved in the presentinvention.

[0016] As the display area is sealed within the cap and the completelycured photosensitive glue, the internal device of the display will notbe damaged by the moisture penetration.

[0017] The present invention thus improves the defect of theconventional structure and process, such that the reliability of thedisplay is enhanced.

BRIEF DESCRIPTION OF DRAWINGS

[0018] These, as well as other features of the present invention, willbecome more apparent upon reference to the drawings.

[0019]FIG. 1 shows a top view of a conventional active matrix organiclight emitting diode display.

[0020]FIG. 2 shows a cross sectional view along the line I-I″ as shownin FIG. 1.

[0021]FIG. 3 shows a top view of an active matrix organic light emittingdiode display according to the present invention.

[0022]FIG. 4 shows a cross sectional view along the line II-II″ as shownin FIG. 3.

DETAILED DESCRIPTION

[0023]FIG. 3 shows a top view of an active matrix organic light emittingdiode provided by the present invention, and

[0024]FIG. 4 shows a cross sectional view along line II-II″ as shown inFIG. 3.

[0025] Referring to FIGS. 3 and 4, a substrate 100 is provided. Thesubstrate 100 comprises a display area 120 and a non-display area 122. Aplurality of pixel structures 107 is formed in the display area 120.Each of the pixel structures 107 comprises an active device (thin-filmtransistor), an anode layer 102, a luminescent layer 104 and a cathodelayer 106.

[0026] While forming the anode layer 102 of the pixel structures 107, aplurality of transparent conductive lines 300 are simultaneously definedin the non-display area 120 extending from two edges of the display area120 to the non-display area 122 for forming a plurality of fan-outs. Inthis embodiment, the length of the transparent conductive lines 300 isabout 2 mm to about 4 mm for providing electrical connection between adriving chip formed subsequently in the non-display area and the pixelstructures 107. Therefore, the signals generated by the driving chip canbe delivered to the pixel structures 107.

[0027] As the transparent conductive lines 300 are definedsimultaneously with the anode layer 102, the material for forming thetransparent conductive lines 300 is thus the same as that of the anodelayer 102. The material includes indium tin oxide or indium zinc oxide.

[0028] A photosensitive glue 112 is formed at a perimeter of the displayarea 120 on the substrate 100. An encapsulate cap 114 is disposed overthe substrate 100 and adhered thereto via the photosensitive glue 112for covering the display area 120. The material for forming the cap 114includes impermeable metal or glass. The photosensitive glue 112includes an UV glue, for example.

[0029] An UV radiation 116 is then performed to cure the photosensitiveglue 112. Meanwhile, as the transparent conductive lines 112 extendingfrom the display area 120 to the non-display area 122 are transparent,the UV radiation 116 can be absorbed by every part of the photosensitiveglue 112, which can thus be completely cured. As a result, an improvedpackage and isolation effect can be obtained by the cured photosensitiveglue 112.

[0030] A driving chip 110 is then formed in the non-display area 122 ofthe substrate. The electrical connection between the driving chip 110and the pixel structures 107 is achieved via the conductive transparentlines 108.

[0031] Therefore, the active matrix organic light emitting diode displayprovided by the present invention comprises a substrate 100, a drivingchip 110, a plurality of transparent conductive lines 300, anencapsulating cap 114 and a photosensitive glue 112.

[0032] The substrate 100 has a display area 120 and a non-display area122, where the display area 120 further comprises a plurality of pixelstructures 107, each including an active device (thin-film transistor),an anode layer 102, a luminescent layer 104 and a cathode layer 106. Thedriving chip 110 is located in the non-display area 122. A plurality oftransparent conductive lines 300 is formed on the substrate 100. Thetransparent conductive lines 300 extend from the display area 120towards the non-display area 122 to electrically connect the pixelstructures 107 and the driving chip 110. The material for forming thetransparent conductive lines 300 includes indium tin oxide or indiumzinc oxide.

[0033] The encapsulating cap 114 is located over the substrate 100 tocover the display area 120 of the substrate 100. The photosensitive glue112 is applied along a perimeter of the display area 120 on thesubstrate 100 to adhere the cap 114 and the substrate 100.

[0034] It is appreciated that while forming the transparent conductivelines 300, a power source line (not shown) may also be formed in thenon-display area 122 of the substrate 100. The power source line iselectrically connected to the pixel structures 107 to provide sourceenergy to the pixel structures 107 from an external power supply.

[0035] In addition, although the transparent conductive lines 300 (madeof indium tin oxide or indium zinc oxide) for connecting the pixelstructures 107 and the driving chip 110 has resistance relatively higherthan that of metal, as the typical driving chip 110 hardly requires alarge current, and the length of the transparent conductive lines 300 isonly about 2 mm to about 4 mm (the distance between the pixel structures107 and the driving chip 110), the effect upon signal attenuation isvery minor. Further, should signal is attenuated thereby, theattenuation can be compensated by increasing the signal voltage outputfrom the driving chip 110.

[0036] Accordingly, the present invention has the following advantages.

[0037] 1. The present invention uses transparent conductive lines toprovide electric connection between the pixel structures and the drivingchip instead of using the fan-outs described above. Therefore, theproblem of incomplete curing the UV glue is resolved in the presentinvention.

[0038] 2. As the display area is sealed within the cap and thecompletely cured photosensitive glue, the internal device of the displaywill not be damaged by the moisture penetration.

[0039] 3. The present invention thus improves the defect of theconventional structure and process, such that the reliability of thedisplay is enhanced.

[0040] Other embodiments of the invention will appear to those skilledin the art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples to be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

1. A method of fabricating an active matrix organic light emittingdiode, comprising: providing a substrate having a display area and anon-display area thereon, wherein the display area comprises a pluralityof pixel structures thereon; forming a plurality of transparentconductive lines electrically connected to the pixel structures andextending from the display area towards the non-display area; disposinga cap over the substrate to cover the display area; applying aphotosensitive glue at a perimeter of the display area between the capand the substrate, so that the cap is adhered to the substrate thereby;performing a radiation step to cure the photosensitive glue; and forminga driving chip in the non-display area of the substrate, wherein thedriving chip is electrically connected to the pixel structures via thetransparent conductive lines.
 2. The method according to claim 1,wherein the transparent conductive line is made of indium tin oxide orindium zinc oxide.
 3. The method according to claim 1, wherein thetransparent conductive line has a length of about 2 mm to about 4 mm. 4.The method according to claim 1, wherein the photo-sensitive glueincludes an ultra-violet glue.
 5. The method according to claim 4,wherein the radiation step further comprises an ultra-violet radiationstep.
 6. The method according to claim 5, wherein the cap includes metalcap or a glass cap.